In the printing arts high speed roto presses can print books, newspapers and the like products at very high speeds such as 90,000 per hour and supply these products in shingled form on output on-line conveyor streams. Because of the nature and speed of such equipment the shingled products do not have precisely controlled shingle spacing distances. These spacing distances tend to change with speed of the press and randomly for various reasons including frictional drag and defective products, etc. Thus, any on-line processing equipment need have the capabilities of operating at very high speeds to process products of variable spacing. If this is possible, further on-line processing equipment, such as trimmers, addressers, inserters, staplers, folders, etc., need be complex and expensive to process such randomly variable product spacings.
Because of this problem the capabilities of the high speed presses in the prior art have been more theoretical than actual, since they may need be slowed down to conform with the down stream processing equipment capabilities. The problem is even more complicated when it is necessary to use the down stream processing equipment for widely varying speeds, such as those encountered during press start up and shut down operations.
Because of these problems it has been customary in the high speed rotary press art to stack and store the products for processing by other down stream equipment. Representative prior art relating to the stacking and processing of printed products is found in patents to W. H. Weidman, U.S. Pat. No. 3,053,532, Sept. 11, 1962 and S. F. D'Amato, et al., U.S. Pat. No. 3,907,274, Sept. 23, 1975, and I. F. Niles, et al., U.S. Pat. No. 2,673,735, Mar. 30, 1954 and A. R. Stobb, U.S. Pat. No. 4,555,101, Nov. 26, 1985.
It is however an object of the present invention to provide an on-line printing system for processing high and variable speed press output streams that is compatible with state of the art down stream processors for shingled products.
In high speed on-line processors, it has been known to divert streams of products into alternative paths in batches as represented for example by patents to M. S. Chandhoke U.S. Pat. No. 4,424,966, Jan. 10, 1984 and F. Achelpohl et al. U.S. Pat. No. 4,266,654, May 12, 1981. One known mechanism provides for the combining of two successive shingled products into single gripper clamps of a set of cyclically presented such clamps for further processing at substantially lower product per hour rates, namely as set forth by W. Reist in U.S. Pat. No. 4,333,559, June 8, 1982. However, the processing of shingled stacked pairs of products in down stream equipment is unconventional and poses significant problems.
Therefore the prior art has not provided appropriate means or systems for segregating alternate ones of shingled products at on-line press delivery speeds into two streams at delivery speeds which can be processed by state of the art down stream equipment. Nor has equipment been provided for merging two on line streams of shingled products into a single stream of shingled products, which permits simplified systems having a single downstream line of further processing equipment.